package com.cse.utils;


import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.cse.constants.RedisConstants.*;


@Component
@Slf4j
@RequiredArgsConstructor
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    public void set(String key,Object value ,Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }


    public void setWithLogicalExpire(String key,Object value ,Long time, TimeUnit unit){
        //设置逻辑过期
        RedisData redisDate=new RedisData();
        redisDate.setData(value);
        redisDate.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisDate),time,unit);
    }

    //解决缓存穿透
    public <R,ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID,R>dbFallback,Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(json)) {
            return JSONUtil.toBean(json,type);
        }
        if (json!=null) {
            return null;
        }
        R r=dbFallback.apply(id);
        if (r==null){
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        this.set(key,r,time,unit);
        return r;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);

    //解决缓存击穿
    public <R,ID>R queryWithLogicalExpire(
            String keyPrefix,ID id,Class<R> type,Function<ID,R>dbFallback
            ,Long time, TimeUnit unit
    ) {
        String key = keyPrefix + id;
        //Redis里面查询缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        //如果不存在，直接返回
        if (StrUtil.isBlank(json)) {
            return null;
        }
        //命中 先把json反序列化未对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
       R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
        //判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //未过期，直接返回店铺信息
            return r;
        }
        //已过期，重建缓存
        //获取互斥所
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock= tryLock(lockKey);
        //判断是否获取锁成功
        if (isLock) {
            //获取锁成功，开启独立线程重建缓存
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    R r1=dbFallback.apply(id);
                    this.setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unLock(lockKey);
                }
            });

        }

        return r;
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }




}
